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A 2002 report by the National Association of Clean Water Agencies indicated that dental clinics are the largest source of mercury in wastewater. To reduce this discharge, many dental offices are using amalgam separators.
By Nikki Stiles
In some ancient cultures mercury was thought to prolong life, heal fractures, and maintain health. China’s first emperor, Qin Shi Huang Di, was thought to be buried in a tomb that contained rivers of flowing mercury, which represented the rivers of China. Ironically, it was probably the mercury pills that the emperor ingested to supposedly give him eternal life that led to his insanity and ultimate death.
Despite potential health hazards, mercury can still be found in thermometers, blood pressure devices, lab chemicals, cleaners, and amalgam dental fillings. However, the use of it is on the decline, and disposal methods are approached much more cautiously. The EPA has also taken an interest in mercury, and regulations are currently being enforced in many areas of the United States.
What Is Amalgam?
Mercury occurs naturally in deposits throughout the world, and it is harmless in an insoluble form, such as mercuric sulfide, but it is poisonous in soluble forms such as mercuric chloride or methyl mercury. Human activities, such as burning coal or using mercury to manufacture certain products, have increased the amount of mercury in the environment. One of those sources of mercury is contained within many of our mouths in the form of amalgam dental fillings. Amalgam is any mixture or blending of mercury with another metal or with an alloy.
Amalgams are used in dentistry because they are cheap, easy to use, and more durable than many alternatives. Amalgams are generally composed of 69.4% silver, 3.6% copper, 26.2% tin, and 0.8% zinc in powder component and have liquid component of 42% to 45% mercury by weight. The amalgam remains soft for a short time so it can be packed and fill any irregular volume and then forms a hard component. During the process of installing or removing these amalgam fillings, particles of amalgam are discharged into the dental unit vacuum line. Most amalgam particles are captured by chair-side traps and suction system traps and filters. Particles not captured end up in the wastewater discharged from the dental office. A report released in 2002 by the National Association of Clean Water Agencies indicated that dental clinics are the largest source of mercury in wastewater as compared with other groups of users discharging to wastewater treatment plants. To reduce this discharge, many dental offices are using amalgam separators.
How Amalgam Separators Work
Amalgam separators are devices used to remove amalgam particles from dental office wastewater using sedimentation, filtration, chemical removal by ion exchange, or a combination of the technologies. Amalgam separators are usually installed at each chair or in a central location that receives wastewater from all chairs where amalgam is removed or placed.
Amalgam separators on the market are certified using an ISO standard (ISO 11143) that focuses on percent particle removal, which is 95%, utilizing a standard amalgam sample suspended in water.
A research paper entitled “Evaluating Amalgam Separators Using an International Standard,” cowritten by Hanu Batchu, M.S.; Duane Rakowski, B.S.; P.L. Fan, Ph.D.; and Daniel Meyer, D.D.S., evaluated 13 amalgam separators and two filtration devices. The results of this study concluded that all the devices exceeded the ISO standard.
Once the amalgam is filtered out by an amalgam separator, it is usually sent to a recycling facility. “In most cases, depending on the requirements, it’s recycled,” says Al Dubé, vice president of sales for the dental division of SolmeteX, a company that produces amalgam separators. “For us, we sell a package with a new cartridge or container, and that container also includes shipping directly to our recycling center.
“Mercury is no longer mined. Anything that is currently being put back into the industry is recycled,” says Dubé.
Health Effects of Mercury in the Environment
According to the EPA, the primary way people in the United States are exposed to mercury is by eating fish containing methyl mercury. Small organisms take up methyl mercury as they feed. When the larger animals eat the smaller ones, they also take in methyl mercury. The larger fish, such as sharks and swordfish, have much greater concentrations of methyl mercury.
Almost all people have trace amounts of methyl mercury in their tissues. There are many factors that determine the effects of mercury exposure on a person. These include the chemical form of mercury, the dose, the age of person exposed, the duration of exposure, the route of exposure (such as inhalation, ingestion, or dermal contact), and the person exposed. For fetuses, infants, and children, the primary health effect of methyl mercury is impaired neurological development. Methyl mercury exposure in the womb, from the mother’s consumption of fish and shellfish that contain methyl mercury, can adversely affect a baby’s growing brain and nervous system. Impacts on thinking, memory, attention, language, and fine motor and visual spatial skills have been seen in children exposed to methyl mercury in the womb.
Although health effects of mercury are somewhat controversial, outbreaks of methyl mercury have revealed that adults, children, and developing fetuses are at risk from exposure to methyl mercury.
One such outbreak occurred in Minamata, a city in the Kumamoto prefecture in Japan in 1956. The Chisso Corp. chemical factory operated from 1932 until 1968 and released methyl mercury into its industrial wastewater. This methyl mercury accumulated in the shellfish and fish in Minamata Bay and the Shiranui Sea. The shellfish were subsequently eaten by the local population.
Some of the locals began experiencing symptoms consistent with severe mercury poisoning. What is now known as Minamata disease includes symptoms such as ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision, and damage to hearing and speech. In extreme cases, psychosis, paralysis, coma, and death follow within weeks of the onset of the symptoms. As of March 2001, a total of 2,265 victims had been recognized (1,784 have died), and more than 10,000 have received financial compensation from the Chisso Corp. Lawsuits and claims for compensation continue to this day.
Elemental mercury effects cause health problems when mercury is breathed as a vapor and absorbed through the lungs. These exposures generally occur when elemental mercury is spilled or products that contain elemental mercury break and expose mercury to the air. Symptoms from this exposure include tremors, emotional changes, headaches, disturbances in sensations, changes in nerve responses, and performance deficits on tests of cognitive function.
High exposures to inorganic mercury can result in damage to the gastrointestinal tract, the nervous system, and the kidneys. Symptoms of high exposure to inorganic mercury include skin rashes and dermatitis, mood swings, memory loss, mental disturbances, and muscle weakness.
Other Ways Amalgam Gets Into the Environment
Not only does mercury enter the water supply, but it enters the atmosphere and land as well. “About 30% to 40% of sewage treatment sludge is still incinerated. This releases the mercury from the amalgam,” says Dubé. “Even if it’s not incinerated, it will go in the landfill.”
These landfills are the prime environment for that mercury to methylate and get into the atmosphere via pipes outcast from the landfills, says Dubé. “The other thing that happens with sewage sludge—and it is kind of a growing industry—is that they are making fertilizer out of it and selling it to homeowners and farmers. So now not only is it getting into landfills, but now you are spreading it on the surface.
“One of the things that the EPA has is called P2, pollution prevention; and pollution prevention means point source, getting it at the source before it gets into the soil, and that’s where a lot of these new regulations are being generated from,” says Dubé.
Regulations
“There is really a growing trend for the requirements of amalgam separators,” says Mark Stone, project manager for the Naval Institute for Dental and Biomedical Research. “The reason for this is that many local regulators are now requiring them.”
Regulations vary from state to state and sometimes county to county. Currently nine states require dental offices to install amalgam separators. One example of a county that has successfully integrated amalgam separator requirements for dental offices is in the Seattle–King County area in Washington state. In 1995, King County and the Seattle–King County Dental Society began working with dentists to achieve voluntary, proper disposal of wastes. Initially, this voluntary effort fell flat. “In 2000, the group that was doing the voluntary compliance arm did a study and found out that we didn’t have voluntary compliance,” says Patricia Magnuson, industrial waste investigator for the Department of Natural Resources and Parks in the King County wastewater treatment division. King County’s Local Hazardous Waste Management Program and the King County Industrial Waste Program began working with the Seattle–King County Dental Society and others to identify a user-friendly process for all dental practices in the King County sewer service area to follow to ensure that they were in compliance with wastewater discharge limits.
“For small discharges as opposed to industrial discharges, they have to meet a local limit of 0.2 parts per million. Through research that had been done, it was pretty clear that dentists could not meet that local limit. So we started enforcing existing regulations. We gave them the option of applying for a discharge permit or to install amalgam separators, which we had determined would allow them to fairly consistently meet our local limits,” says Magnuson.
By the end of 2003, 97% of the dental practices in the county’s sewer service area, which Magnuson estimates to be around 1,000 offices, were in compliance with these regulations. “We’re seeing a pretty good success rate. We’re doing compliance inspections, and dentists are pretty much in compliance,” she says. The results have been a significant reduction in silver and mercury concentrations in the county’s biosolids.
Olivia Stapelman, health and environmental investigator for Public Health Seattle and King County, and who also worked in the dental community to achieve compliance, says another problem the county faces is that of regulating the amount of mercury at dental offices with onsite sewage systems. She has worked with these offices, and their onsite sewer systems contained “really, really high” levels of mercury. “Unfortunately, we don’t have any clear information about whether amalgam separators work well enough to reduce the amount of mercury in the sewage to the point where it can be accepted at a sewage treatment plant, but as it stands now there was so much mercury in the septic tanks that it has to be handled as hazardous waste,” says Stapelman.
Another way to prevent large amounts of amalgam from entering the water and wastewater is by facilities practicing best management practices (BMPs). “Probably the first line of defense is best management practices, which are a number of practices done in the office that in combination with amalgam separators demonstrates to be very effective in decreasing mercury in the wastewater,” says Stone.
BMPs for the dental practices in King County sewer service area include the following:
- Keeping amalgam out of sinks and never rinsing amalgam waste down the drain
- Cleaning or replacing chair-side traps on regular schedule and properly disposing of amalgam waste
- Cleaning vacuum pump filters regularly, according to the manufacturer’s recommendations, and properly disposing of amalgam waste
- Sending amalgam wastes to a licensed treatment, storage, disposal, or recycling facility
- Maintaining all disposal records onsite for three years
Companies That Specialize in Amalgam Separators
There are roughly eight companies that manufacture amalgam separators in the United States. As mentioned earlier, SolmeteX is one such company. The company produces a series of separators in various sizes called the Hg5 series. According to the company, these systems require no maintenance and can be used for wet or dry vacuum systems. The company also provides recycling services. The recycling program includes Department of Transportation–approved packaging and shipping materials; transportation to and from the dental office by an authorized carrier; recycling by an authorized recycling facility; recycling certificate mailed to the dental office; and cradle-to-grave tracking.
Another company, Pure Water Development LLC, originated in Europe, where it goes by the name of Metasys. Bruno Pregenzer founded the company in 1988. “Mercury in drinking water is a big topic, so we keep expanding,” says Daniela Gebhart, marketing department representative for Metasys.
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Photo: Pure Water Development LLC |
| Amalgam separators are a way to avoid
mercury pollution in water sources. |
Pure Water Development produces an amalgam separator called the ECO II Amalgam Separator, which is designed to accompany six dental chairs or more. The Metasys company produces an amalgam separator called MST 1. The company offers recycling of amalgam waste worldwide and has developed its own amalgam sludge recycling system. After amalgam sludge is transported to Austria, hazardous mercury and other metals are extracted from the waste. The materials collected are then reused as raw material in industrial applications. Pure Water Development is registered with the Department of Environmental Protection and the EPA in the state of Florida (FLR000095208) to handle amalgam waste.
Ross M. Fraker used his background as both a dentist and an engineer to design the Amalgam Collector for his business, R&D Services Inc. “My background as an engineer helped me invent the Amalgam Collector, and then my background as a dentist helped me sell them, because I understand the dental office fairly well,” says Fraker, president and chairman of the board of directors of R&D Services Inc.
Fraker began his company in 1994 and has 4,000–5,000 customers in the US, Canada, and New Zealand. In 2001, a research study conducted by the American Dental Association found that the Amalgam Collector was 99.9% efficient at removing the amalgam particles used in the international standards test, the ISO 11143-1999.
According to Fraker, “The main thing that makes mine different is that I collect all of the fluid that comes out of the dental offices before it goes to the collection system and then allow gravity to do the actual separating of the heavy particles from the fluid in an overnight period. I give it more time to settle.”
The Amalgam Collector standard model requires a small amount of maintenance. “The economy model requires a 30-second job by the dental staff first thing in the morning to have the collection system decant the clear water off of the top of the sediment. I have an enhanced version that does this same type of job automatically,” Fraker says.
Step in the Right Direction
Not only does mercury get into the environment through dental facilities; medical facilities contribute to this problem as well. The Hospitals for a Healthy Environment program has a goal to eliminate mercury from the health care wastestream. So far, 4,000 health care facilities in the United States have pledged to become mercury free.
Further strides were made in the dental community in October 2007, when the American Dental Association (ADA) updated its BMPs for the disposal of dental amalgam waste to include the use of separators, collection devices installed in dental office plumbing to capture and remove at least 95% of solid waste particles before they enter the sewer system.
“Dentists across the country have enthusiastically embraced the ADA’s best management practices since we introduced them in 2003, which clearly demonstrates that voluntary programs work,” says Mark J. Feldman, ADA president, in a recent press release. “Since then, we have gained a lot of experience with separator technology and even assisted in the ISO in developing standards for these devices. We have learned that the systems work well, and we now feel comfortable including them in our best management practices recommendations.”
According to the press release, dental offices using ADA BMPs already capture about 80% of waste amalgam, and adding separators will increase that amount to 95%.
“Like most people, dentists are committed to protecting the environment,” says Jim Bramson, ADA executive director. “By adding separators to their best management practices, dentists have much greater control in their efforts to ensure a healthier environment for everyone.”
Nikki Stiles is a freelance writer based in Fairmont, WV.
OW - January/February 2008
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